(struct name (field1 field2 ...)) - Creates a new structured type,
with methods named name, name? name-field1, name-field2,
and so on and so forth.
a. Start DrRacket.
b. Grab the code for this lab.
c. Grab an additional code file for the lab.
d. Do the lab.
This lab was (mostly) newly written in spring 2019. The code was
extracted to a separate file in Fall 2021. Fall 2021 saw the
arrival of a new problem (chirps-by and chirps-tagged-with),
the de-emphasizing of the hash table problem, and the addition
of a few new extras (ordering of dates, selecting chirps by
date). Spring 2022 saw the addition of the date.rkt file.